Coronary Stents

Coronary Stents

Why Use a Stent?

Here's an update about drug coated stents

Stents are used in coronary 'Revascularization" or 'Angioplasty' procedures. These procedures are sometimes referred to as PCI- Percutaneous Coronary Interventions. PCI procedures are performed in the cardiac catheterization lab and are non-surgical treatments for coronary artery disease. These procedures usually last 1-2 hours and most patients are discharged home within 1 or 2 days after a successful procedure.

Stents are used World-Wide and are currently employed in over 70% of all PCI procedures. They have gained widespread acceptance because of two very important reasons:

1) Stents reduce the likelihood of 'Acute Closure' during a coronary revascularization procedure. That is, they reduce the likelihood that a treated coronary artery will close down (occlude) completely over the next 12-24 hours. Acute closure used to occur in approximately 5-10% of all balloon angioplasty procedures within the first 24 hours. In fact, most cases of acute closure occurred within minutes of the procedure with the patient still on the table. When acute closure occurred, it was a medical emergency with many patients suffering large heart attacks or requiring emergency cardiac surgery. With the advent of stents, acute closure is extremely rare. Consequently, stents have made PCI procedures safer.
2) Stents are proven to reduce the incidence of 'Restenosis'. Restenosis generally occurs within 4-6 months following a PCI procedure. Before stents, the incidence of restenosis was about 35-45%. Restenosis is a re-narrowing of the treated coronary artery which is largely related to the development of neo-intimal hyperplasia that occurs within an artery after it has been treated with a balloon or atherectomy device. In a sense, restenosis is scar tissue that forms in response to a mechanical intervention within a vascular structure. Restenosis is different than atherosclerosis which is related to calcium, fat, and cholesterol plaque build-up. Some people are more prone to developing restenosis than others. Stents are the only widely available PCI device that have been proven to reduce the incidence of restenosis. Stents reduce restenosis by approximately one-third. While they do not offer a 'cure' for coronary artery disease, they do have a major impact on decreasing the need for a repeat procedure.

What is a Stent?

Stents are stainless steel or nytinol mesh like devices that look similar to the spring in a pen. Stents are delivered into the coronary artery on a catheter during a PCI procedure. They are then 'deployed' in the artery by either expansion by a balloon or by a unique 'self expanding' delivery design. They serve as a scaffold to prop the inside of the artery (the lumen) open which increases blood flow to the heart muscle. They are permanently deployed devices that stay in the artery. They are not removed. They ultimately become covered with cells and in essence become part of the artery over time. One of the early limitations to stent use was the development of 'Subacute' stent closure which occurred when blood clots formed within the stent to shut off blood flow to the heart muscle. Like acute closure, this frequently resulted in a heart attack or other major complication. Fortunately, it became recognized that stents had to be deployed within the artery in a certain manner and that anti-platelet drugs were necessary for the prevention of subacute closure. With modern techniques and the use of Aspirin and oral anti-platelet drugs (Plavix or Ticlid), subacute stent thrombosis is extremely rare occurring in approximately 1 to 1.5%. Pictured is a Velocity Stent from Cordis.

Stents have revolutionized the catheter treatment of coronary artery disease. Research continues in an effort to find better materials and procedures to lower restenosis rates even further. One area receiving attention is the use of radiation therapy to prevent restenosis. Early research shows that radiation is effective but until larger trials can confirm this information, radiation or 'brachytherapy' remains a research tool.

UPDATE 2001: Brachytherapy Now Available to Treat Restenosis!

UPDATE May, 2000: While it has been known that treatment with Ticlopidine may result in Thrombotic Thrombocytopenic Purpura or TTP, a rare acquired blood disorder, recent evidence now shows that TTP may also occur in patients treated with Plavix (Clopidogrel). This rare disorder is characterized by microangiopathic anemia, fever, thrombocytopenia, renal dysfunction, and neurologic dysfunction.

UPDATE August, 2000: The CLASSICS study finds that Clopidogrel (Plavix) is safer and as effective as Ticlopidine (Ticlid) after stenting. CLASSICS randomized over 1,000 patients to Clopidogrel (75 mg per day after a 300 mg load) versus Ticlopidine (250 mg 2x per day). All patients also took aspirin. Safety was significantly improved with Clopidogrel in comparison to Ticlopidine. Efficacy was similar in the two groups. (Bertrand et al, Circulation 2000;102:624)

To learn more about stents or other PCI devices, please call or email us.

External Links to Leading Stent Companies:

Cook Cardiology (Gianturco-Roubin Stents)
GUIDANT/ACS (Multilink/Duet/Tetra/Penta/Zeta Stents)
SCIMED/BOSTON SCIENTIFIC (Nir/Wall Stents/Taxus)
Medtronic/AVE (GFX/S series Stents)
J ohnson & Johnson/Cordis (Cypher Stents)